The present invention broadly relates to fire detectors and, more specifically, pertains to a new and improved construction of a fire detector equipped with a sensor for detecting a physical quantity or parameter such as heat, light or smoke and which, in particular, is capable of storing output levels reached by the sensor at the time of response of the fire detector and also prior to response of the fire detector is capable of storing output levels reached at each of a succession of predetermined time intervals together with the respective time values until the fire detector responds, and of displaying such stored data whenever necessity arises later.
Generally speaking, the fire detector of the present invention stores the time when a fire detector responds or generates an alarm and also stores the output level of the sensor at that time so that these stored data may be displayed later whenever required.
In other words, the fire detector of the present invention comprises a sensor for detecting a physical quantity such as heat, light or smoke and the sensor has a signal output level which changes in response to changes in such physical quantity. The fire detector constantly monitors changes in the signal output level of the sensor and responds or generates an alarm when the signal output level exceeds a prescribed reference or set level. The fire detector further comprises first storage means for storing a value of the time at which the fire detector responds or generates an alarm and for storing a value of an output level of the sensor at such time.
Conventional fire detectors of this kind continuously monitor changes in the output level of a sensor and respond or generate an alarm when a predetermined reference or set level is exceeded. Therefore, even though the response of the fire detector indicates that the output level of the sensor has exceeded the predetermined reference or set level, the actual output level and the time at which the fire detector responded and, moreover, changes or variations in the output level before the fire detector responded, cannot be determined later. Therefore, it has heretofore been impossible to accurately determine the cause of false alarms produced by such fire detectors.